1. Field of the Invention
The present invention relates to compressor valves and particularly to a compressor valve with a light weight synthetic valve plate having a single spring loaded steel ring dampening system.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
A good compressor valve has to be efficient and last long. The efficiency is simply a function of the area the valve provides when it is open since the valve is practically an orifice, causing a pressure drop across it which means loss of horsepower. Valve life is achieved by limiting the impact of the valve plate when it opens as well as when it closes. The opening impact can be controlled by limiting the valve lift since the valve plate accelerates over the whole lift, which means the higher the lift, the higher the opening impact. A high lift increases the valve area, to lower the pressure drop. With mass dampening, the opening impact can be reduced. The travel of the damping ring is only important, since the later the valve plate meets the ring, the higher the velocity of the valve plate is and therefore it's energy is higher. A damping lift of 0.015 to 0.020″ is sufficient.
Some plate valves use a “double dampening” system. These are basically two plates of the same configuration but the “damping plate” has a stop on the ID limiting its travel to something less than that of the valve plate. Plate valves for reciprocating compressors commonly use a simple spring loaded valve plate. The assumption is that the springs cushion the opening impact of the valve plate and initiate the closing motion of the valve plate before the compressor piston reaches the end of the intake or discharge stroke, so by the time the piston reaches the end of the stroke the valve is closed. There are valves which apply a wafer type spring instead of coil springs which improves the cushioning ability of the spring, since wafer type springs have a non-linear spring characteristic.
There are plate valves known which employ in addition to the valve plate so called damping plates. The damping plates have the same porting as the valve plate and are positioned somewhere between the valve plate and the guard or stop plate. Both plates are guided by a guide ring or are centered on the assembly bolt. Commonly, the valve plates have their own set of springs, which at the valve opening have really no dampening effect. The dampening effect is caused by the mass of the damping plates which, when the valve plates hit the damping plates, have to be accelerated and thereby reduce—or at least check—the velocity the valve plate is traveling with, and therefore reduce the opening impact.
Since the valve plates hardly ever move parallel to the valve seat, the valve plate always makes contact with the damping plate(s) on the outer diameter causing a tilt of the damping plates and also a leveling and a reduction of speed of the valve plate. The only thing which matters here are the mass of the valve plate and the damping plates. The springs have very little effect. The end result is a reduced impact velocity of the valve plate against the guard, thereby prolonging the valve plate life.
U.S. patent application No. 20020144733, published Oct. 10, 2002 by Artner, concerns a ring plate valve for piston compressors, which includes several individual plastic ring plates as closing organs, which are concentrically arranged in relation to each other between valve seat and catcher. The diameter of individual steel spiral springs, that are distributed on the circumference for the purpose of supplying the ring plates with spring force, is essentially equally large as the width of the ring plates, thereby allowing for the realization of a small spring length. On the side of the catcher, the spiral springs are supported and guided inside individual spring cups, preferably of abrasion-resistant plastic.
U.S. Pat. No. 4,854,341, issued Aug. 8, 1989 to Bauer, is for a compressor plate valve having a valve seat with flow passages, a valve guard and a valve plate formed from concentric rings joined together by radial webs. In order to damp the valve plate, and in particular to lessen its impact both on opening and on closing the valve, and to reduce troublesome adhesion between the plates, the valve plate comprises a closure plate of soft material such as plastics, and a guide plate of hard material such as steel. The two plates have the same outline in plan view and lie firmly against each other, the soft closure plate facing the valve seat and the guide plate facing the valve guard. Only the outer ring of the two plates is loaded by springs and is substantially wider than the inner rings.
U.S. Pat. No. 4,852,608, issued Aug. 1, 1989 to Bennitt, concerns a plate-type fluid control valve, which has a ported valve seat, stop plate, and valving element (movable between the plate and seat) biased toward the seat by compression springs. Eight sets of compression springs are employed, in the disclosed embodiment, and each set comprises a pair of helical, counterwound (compression) springs concentrically nested together.
U.S. Pat. No. D336,680, issued Jun. 22, 1993 to Safford, shows the ornamental design for a plate valve bumper.
U.S. Pat. No. 3,428,082, issued Feb. 18, 1969 to Kohler, claims a valve for piston-type compressors comprising a valve seat, a valve guard arranged in a spaced relation to the valve seat, a valve plate disposed between the valve seat and the valve guard, a guide plate for frictionless guidance of the valve plate, and a spring means between the valve plate and the guide plate.
U.S. Pat. No. 1,695,069, issued Dec. 11, 1928 to Tuttle, describes compressor plate valve comprising a valve seat, an annular flat valve plate arranged on the face of the valve seat, and a separate spring guide plate which rests on top of the valve plate.
U.S. Pat. No. 6,817,846, issued Nov. 16, 2004 to Bennitt, discloses a gas compressor and method according to which a piston assembly reciprocates in a bore to draw the fluid to be compressed into the bore during movement of the piston unit in one direction and to compress the fluid during movement of the piston unit in the other direction. FIG. 3 shows an annular dampening plate which is disposed adjacent the valve plate and functions to decelerate the valve plate under conditions to be described to prevent damage caused by impact inertia.
U.S. Pat. No. 3,703,912, issued Nov. 28, 1972 to Bauer, concerns a plate valve especially adapted for use in reciprocating compressors and comprising a valve seat, a valve guard spaced from the valve seat, a valve plate serving as a closing member, and a damping plate interposed between the valve plate and the valve guard.
U.S. Pat. No. 2,870,783, issued Jan. 27, 1959 to Kehler, is for an annular plate valve which has a valve plate, a damping plate, and a spring plate. The spring plate has spring blades thereon which pass through apertures on the damping plate to contact the valve plate, and short spring blades which contact the damping plate.
U.S. Pat. No. 5,036,880, issued Aug. 6, 1991 to Safford, puts forth a valve for reciprocating compressors generally comprising a seat member, a movable plate member, a flat spring plate, and a guard which are assembled as a unitary structure. The seat member and the plate member have linear fluid passage ports which are offset relative to each other. When the valve is in its normal sealing position, the plate member is pressed by linear spring fingers formed on the spring plate against the seat member causing the surface area of the plate member to block the linear fluid passage ports of the seat member. The plate member also has projections extending in a linear or circular direction to receive the spring fingers. When the pressure in the reciprocating compressor becomes sufficiently great, the plate member moves backwards against the spring plate allowing the fluid to move through the valve, including the linear fluid flow passages of both the seat member and plate member.
U.S. Pat. No. 6,510,868, issued Jan. 28, 2003 to Penza, puts forth a compressor valve having a valve seat, a valve guard and a sealing plate with contoured sealing surfaces, the valve seat having defining inlet flow ports for admitting a controlled medium into the valve, the lower surface of the valve seat including at least one seating surface, the a valve guard having a recessed area and defining outlet flow ports for discharging a controlled medium from the valve, the sealing plate being positioned within a cavity between the valve guard and valve seat and moves relative to the lower surface of the valve seat between an open and closed position, the upper surface of the sealing plate defining at least one contoured sealing surface for engaging at least one seating surface of the valve seat along a continuous line of contact when the valve is in the closed position.
U.S. Pat. No. 7,011,111, issued Mar. 14, 2006 to Spiegl, indicates sealing elements for compressor valves. The sealing elements are made of synthetic material having embedded fiber reinforcement, as it has been used for some time for automatic compressor valves, the fiber reinforcement consists of at least one piece of an essentially flat, non-woven fiber fabric, which has, at least in its plane, a directionally independent (random) fiber orientation. Disadvantages of short-fibered reinforced synthetic materials can thereby be avoided, as well as the ones for synthetic materials reinforced by means of long-fibered fabrics, and sealing elements may be obtained thereby having a very high durability.
U.S. Pat. No. 1,593,914, issued Jul. 27, 1926 to Redfield, provides a plate valve with an annular valve plate having opposed notches on the outside diameter thereof which is held in place by clips which engage the notches.
U.S. Pat. No. 3,369,563, issued Feb. 20, 1968 to Deminger, claims a plate valve having a damper plate. The plate valve comprises a valve seat, a valve guard, and a valve plate slidably located between the valve seat and the valve guard, at least one damper plate being slidably arranged between the valve plate and the valve guard in a spaced relation to the latter and slidingly guided jointly with the valve plate on a stepped down guide surface, such as a guide ring, the shoulder thus formed limiting the stroke of the damper plate.
U.S. Pat. No. 3,656,500, issued Apr. 18, 1972 to Mayer, Sr., shows a check valve having a generally cylindrical valve chamber with a valve seat surface at one radial wall of the chamber and spring recesses at the opposite radial wall of the chamber. An annular plate seats against the valve seat surface and coil springs in the recesses bear against the annular plate valve to bias it to closed position. Teflon sleeve members in the spring recesses contain the springs and have notched ends which straddle the annular plate and thus locate it centrally of the valve structure. The notches have a depth to permit opening and closing movement of the plate and the sleeves are self-lubricating with respect to the plate edges, the springs disposed within the sleeve, and cylindrical members between the coil springs and the plate and slidable in the sleeves.
Two U.S. patents, U.S. Pat. No. 4,531,541 issued Jul. 30, 1985 and U.S. Pat. No. 4,570,666 issued Feb. 18, 1986 to Hartshorn, disclose a plate-type valve having a valving element movable between a valve guard and a valve seat. The movable valving element has a plurality of flow ports formed therein each of which communicates with a port formed in the valve guard. Too, the valve seat has ports formed therein, but the latter are out of registry with the valving element and valve guard ports. Accordingly, with the element closed upon the valve seat, fluid flow through the valve is prevented, and with the valving element removed from the seat, fluid flow is accommodated. Movement of the valving element away from and then onto the valve seat subjects the ends of the ports in the valving element to fatigue, failure and fracture. The valve seat has a circular recess formed therein, whereat the periphery of the valving element would impact, and loosely set in the recess is an impact ring. Accordingly, the shock of impact of the plate-type element on closing is less likely to precipitate fatigue and failure of the port ends; the periphery of the valving element impacts upon the impact ring, and the latter dissipates the impact forces.
What is needed is a dampening system used in a plate type compressor valve which provides a single steel ring instead of a plate as a dampening element, having the ring supported by either a wafer spring or a set of coil springs, so it will have a very short travel when the valve plate makes contact with the ring, wherein the mass of the steel ring relative to a plastic valve plate allows for a “soft landing” of the valve plate on the valve guard.